Some examples of payment systems involving a mobile phone are as follows:
US Pat. App. 2007/0233615 by Tumminaro, published Oct. 4, 2007, for “Member-supported mobile payment system”;
US Pat. App. 2008/0011825 by Giordano et al., published Jan. 17, 2008, for “Transactions using handheld electronic devices based on unobtrusive provisioning of the devices”;
US Pat. App. 2008/0040265 by Rackley III et al., published Feb. 14, 2008, for “Methods and systems for making a payment via a stored value card in a mobile environment”;
US Pat. App. 2010/0042538 by Dheer et al., published Feb. 18, 2010, for “Money movement network method”;
U.S. Pat. No. 7,689,508 issued Mar. 30, 2010 to Davis et al., for “Mobile device credit account”;
U.S. Pat. No. 7,774,123 issued Aug. 10, 2010 to Pond et al., for “Electronic payment methods for a mobile device”;
U.S. Pat. No. 7,784,684 issued Aug. 31, 2010 to Labrou et al., for “Wireless computer wallet for physical point of sale (POS) transactions”;
U.S. Pat. No. 7,822,688 issued Oct. 26, 2010 to Labrou et al., for “Wireless wallet”;
U.S. Pat. No. 7,8848,980 issued to Carlson on Dec. 7, 2010, for “Mobile payment system and method using alias”;
US Pat. App. 2010/0312703 by Kulpati et al., published Dec. 9, 2010, for “System and method for providing authentication for card not present transactions using mobile device”;
US Pat. App. 2011/0078081 by Pirzadeh et al., published Mar. 31, 2011, for “Mobile payment application architecture”;
US Pat. App. 2011/0093351 by Afana, published Apr. 21, 2011, for “Mobile payment station system and method”;
U.S. Pat. No. 7,933,799 issued Apr. 26, 2011 to Aaltonen et al., for “Method and system for payment and/or issuance of credits via a mobile device”.
Outside the US, a certain M-PESA system is another example. In the US, recently Google has been announcing an upcoming Google Wallet payment system.